Cod sursa(job #555226)

Utilizator CosminDDorcu Cosmin CosminD Data 15 martie 2011 12:48:15
Problema Ciurul lui Eratosthenes Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 
#include <fstream>
#define NMax 2000001
using namespace std;

ifstream fin("ciur.in");
ofstream fout("ciur.out");
int a[NMax],n,sol;

int main()
{
	int i,j;
	fin>>n;
	
	for (i=2;i<=n/2;i++)
		if (a[i]==0)
			for (j=2*i;j<=n;j=j+i)
				a[j]++;
	
	for (i=2;i<=n;i++)
		if (a[i]==0)
			sol++;
	fout<<sol;
	
	fout.close();
	return 0;
}